In the fourth episode of the Climate History Podcast environmental historians John R. McNeill and Dagomar Degroot of Georgetown University discuss the Anthropocene, a proposed geologic epoch distinguished by humanity’s profound alterations of Earth's environment. The concept is much debated and Professors McNeill and Degroot discuss contentious issues such as when the Anthropocene began, the concept’s value, and some criticisms that have been leveled at the proposed epoch. Click here to listen.